Magnetically driven fluidhandling device



Sept. 6, 1949. J STAGGS 2,481,172

MAGNETICALLY DRIVEN FLUID-HANDLING DEVICE Filed May 1?, 1948 20 INVENTO R.

Jesse D. STAGGS 30 t to Y n e Patented Sept. 6, 1949 MAGNETICALLY DRIVEN FLUID- HANDLING DEVICE Jesse D. Staggs, Burbank, Calif.

Application May 17, 1948, Serial No. 27,535

15 Claims. 1

This invention relates to fluid-handling instrumentalities and relates more particularly to magnetically driven pumps, and the like, for handling fluids at high, or relatively high, pressures as well as at low pressures.

Pumps have been proposed in which the impeller or pumping element is driven magnetically by electro-magnetic or permanent magnetic means arranged at the exterior of the pump case and rotated by a power means to drive the impeller within the pump chamber. Similar structures have been proposed employing electromagnets positioned at the exterior of the case and energized to provide a rotating field such as found in an induction motor, to drive the impeller or internal mechanism within the case. The objective sought in these proposals is the avoidance of a rotating shaft passing through the wall of the pump case to drive the impeller and the consequent avoidance of packing for the shaft, the shaft and packing being conventional in directly or positively driven pumps. By eliminating the rotating shaft and packing, the friction inherent in shaft packings is avoided and, of course, there is no fluid leakage problem.

The above referred to magnetically driven pumps, and the like, usually employ a diaphragm closing an end of the pump case and separating the external and internal magnetic elements. It is necessary to make this diaphragm quite thin in order to obtain a sufficient transmission of the magnetic flux or fluid to drive the impeller or internal pump elements. Such thin diaphragms are not sufficiently strong to withstand any appreciable fluid pressure and as a consequence such pumps are not suited for handling or developing high pressures. Thus, while attempts have been made to provide magnetically driven pumps, such activities have, to the best of my knowledge, been restricted to low-pressure devices where the leakage problem at a shaft seal is not really of prime importance and the advantages gained by the magnetic drive are therefore minimized and do not justify the additional expense involved in fabricating and installing the magnetic drive elements.

It is therefore an important object of this invention to provide a fluid-handling mechanism such as a pump capable of handling or developing high, or relatively high, fluid pressures and incorporating a simple, efficient and dependable magnetic drive. The mechanism of the present invention includes a thin diaphragm between the internal and external magnetic elements and which closes an end or wall of the case, the invention being characterized by a means for adequately supporting this thin diaphragm against internal fluid pressure without interfering with the magnetic field or flux flow through the diaphragm. The thin diaphragm 2 of selected material assures a powerful magnetic drive because it permits the internal and external magnetic elements to be arranged in close relation while the diaphragm supporting or sustainmg means dependably reinforces the diaphragm against bursting pressures. Thus the low pressure and/0r weak magnetic drive characteristics heretofore inherent in this type of device have been obviated.

Another object of the invention is to provide a magnetically driven pump of the character above referred to wherein the shaft which supports the freely rotating pump rotor and internal elements-of the magnetic drive serves to support the thin diaphragm against the internal fluid pressures. The shaft, which remains stationary during pump operation, is threaded or otherwise secured to one end wall of the case and extends through the pump chamber to be connected with a reinforcing disc associated with the diaphragm and thus operates to transmit the bursting loads imposed on the diaphragm to said end wall of the case. The reinforcing flange or disc may directly reinforce the major area of the diaphragm so that the principal fluid pressure load is assumed by the disc and shaft.

A further object of the invention is to provide a magnetically driven pump, or'the like, embodying a particularly efilcient or strong magnetic drive which imposes a minimum end thrust on the internal pump mechanism. The drive of the invention comprises annular series of magnets associated with the drive shaft and the internal pump elements and related to develop powerful magnetic circuits for the transmission of rotation and exerting a minimum axial thrust when the pump loads are greatest.

A still further object is to provide a pump of the class referred to wherein the driven internal rotor element of the pump is light in weight, to have low friction and inertia. The construction includes a hollow sealed rotor mounted on the shaft and carrying the internal series of magnets and the pump impeller, the hollow rotor in effect floating in the liquid being handled.

Other objectives and advantages will become apparent from the following detailed description of a typical preferred form of the invention, throughout which description reference is made to the accompanying drawings, in which:

- Figure 1 is a longitudinal sectional view of a pump .constructed in accordance with the invention;

Figure 2 is an enlarged transverse detailed sectional view taken as indicated by line 2-2 on Figure 1;

Figure 3 is an enlarged fragmentary perspective view illustrating the construction of the rotor and the relationship of the magnets; and

Figure 4 is an enlarged fragmentary trans- 3 verse sectional view of the rotor and adjacent parts.

In the drawings I have shown the invention embodied in a centrifugal type pump driven by an electric motor M. It is to be understood that this is but one typical and illustrative application and that the invention may be incorporated in pumps, blowers and related fluid-handling devices of vane, gear, lobe and piston type constructions driven by practically any selected form of power means.

The pum includes a case I having a volute chamber I I and supported by an appropriate base I2. A wall I3 of the case III extends across one end of the chamber II, the opposite end of the chamber being closed by a diaphragm I4 to be subsequently described. A central external boss on the wall I3 has a fluid inlet port I5 which may be provided with threads to facilitate the, connection of a fluid supply pipe (not shown) with the case III. A web I6 extends diametrically through the central inlet port I5. The case I0 has an outlet or high-pressure port I1 extending tangentially from the pump chamber II and passing through an external boss I6 to which the high-pressure fluid line I9 is connected. The case I0 just described may, of course, be con- 'structed of metal and where the pump is intended to handle acids, fruit juices, milk, etc., the case may be constructed of stainless corrosion-resistant metal, glass, ceramic material, or a suitable plastic.

4 through the pump chamber II and has one end screwed into an opening 26 in the abovedescribed web I6 in the fluid inlet port I5. The opposite end portion of the shaft 25 is screw threaded through an opening 21 in the reinforcing disc 24, passing freely through a central opening 28 in the diaphragm I4 in cases where the diaphragm and disc are separately formed parts. Clamp and dome nuts 29 are provided on the projecting end of the shaft 25 at the outer side of the disc 24. With this construction it will be seen that the shaft 25 serves to tie the diaphragm reinforcing disc 24 to the rigid end wall I6 of the case acting under tension to carry the bursting loads imposed on the diaphragm by the fluid in the chamber II. The shaft has a thrust flange 30 adjacent the diaphragm I4 (see Figure 4), and carries a bushing 3I which has a flange 32 engaging against the flange 30.

The internal rotating assembly of the pump includes what I shall term a rotor 33 which serves to carry the pump impeller 34 as well as certain elements of the magnetic drive mechanism. Where practical, I prefer to make this rotor 33 hollow, to reduce its weight and therefore lessen friction as well as inertia effects. In the form of the invention illustrated the rotor 33 comprises two spaced end plates 35 and 36 held The diaphragm I4 mentioned above is a thin disc constructed of a material that is substantially unaffected by magnetism or which has a low magnetic eddy current loss. In practice the diaphragm I4 may be constructed of stainless steel, plastic material or glass. The diaphragm l4, which is substantially parallel with the case end wall I 3, lies against a gasket 20 which in turn engages against a flange 2I on the pump case In. A clamping ring22 is arranged against the outer face of the diaphragm I4 at its periphery and screws or bolts 23 pass through openings in the flange 2I, gasket 20, diaphragm I4 and ring 22 to hold these parts clamped together, to prevent the leakage of fluid at the periphery of the diaphragm.

In accordance with the invention and as above pointed out, a reinforcing flange or disc 24 is associated with the diaphragm M to aid in supporting the same against the pressures exerted by the fluid in the chamber II. In the preferred construction this disc 24 lies at the outer side of the diaphragm I 4 although it may, if desired, be at the inner side. The disc 24 may be constructed as a separate part, as illustrated, in which case it is brazed, soldered, welded or otherwise rigidly secured to and sealed with the outer face of the diaphragm, while in other cases it may be formed as an integral part of the diaphragm. It is preferred to make the disc 24 of substantial diameter so as to reinforce the major area of the diaphragm I4 and, as best shown in Figures- 1 and 4, the external diameter of the disc may be only slightlyless than the internal diameter of the ring 22, leaving a narrow annular channel or gap for the reception of the magnetic drive elements, to be later described. Thus the diaphragm I4 is dependably secured and supported at its periphery by the ring 22, etc. and throughout its major central area by the disc 24. The central portion of the disc 24 is raised or projected somewhat axially outward.

- A shaft 25 extends centrally and axially spaced apart by two or more ring-like spacers 31, the inner spacer serving to seal the inner periphery of the rotor. The outer periphery of the rotor 33 is closed by a rim 38 which may be integral with one of the plates 35 or 36 or formed as a separate part secured and sealed to the plates. The rotor parts may be welded, brazed, soldered or otherwise secured together to form a rigid sealed assembly or, where the rotor is constructed of glass, plastic or the like, it may be an integral hollow casting. The plates 35 and 36 and the inner spacer 31 are rotatably supported by the bushing 3| and the pump impeller 34 is secured to the face of the plate 35 to operate in the chamber II. The rotor 33 is preferably formed of non-magnetic material and where the pump is intended to handle acids or the like, the rotor is formed of corrosion and acid-resistant material such as glass, plastic, or a ceramic. The hollow sealed rotor 33 may substantially displace its own weight in the liquid being handled to "float in the liquid, thus reducing friction at the bushing 3| to a minimum. The plate 36 of the rotor 33 is in spaced adjacent relation to the diaphragm I4 but it is preferred to have only the peripheral portion of the plate in close proximity to the diaphragm and to space the re- 'mainder of the plate a sufiicient distance from the diaphragm to reduce fluid friction or drag.

The above-described shaft 25 for carrying the rotor 33 and for assuming the bursting loads imposed on the diaphragm I4 may be adjusted axially. The screw threads on the opposite end portions of the shaft 25 are pitched in the same direction and have the same leadso that the shaft may be turned manually to adjust it axially. The end of the shaft normally covered by the dome nut 29 is polygonal or slotted to facilitate its manual adjustment.

The magnetic drive of the invention is operable to transmit rotation from an external power shaft to the above-described rotor 33, to operate the impeller 34 or other internal pumping or fluid-handling element. In the drawings I have shown the motor M driving the pump and arranged to have its shaft 40 in axial alignment with the pump shaft 25. A disc or ring-like carrier 4| is keyed or otherwise fixed to the motor shaft 40 to support an annular series of magnets 42. The permanent magnets 42 are of the rod or bar type and project axially from the peripheral portion of the carrier 4| toward the diaphragm l4. The outer or free ends of the magnets 42 are flat and have only slight clearance with the external surface of the diaphragm i4. As shown in Figures 1 and 4, the magnets 42 extend into the annular space or gap between the reinforcing disc 24 and the ring 22, this gap being left or provided to receive the magnets with suitable clearance. In this connection it will be understood that the ring 22 and disc 24 are preferably of non-magnetic material. As the diaphragm i4 is dependably reinforced against bursting loads by the disc 24, the slight clearance between the ends of the magnets 42 and the diaphragm is maintained even when the pump is handling fluid at high pressures. The carrier 4| forms a keeper for the magnets 42, as will later become more apparent, and the magnets are equally spaced apart circumferentially of the carrier.

The magnetic drive further includes an annular set or series of bar-type permanent magnets 43 on the rotor 33. The magnets 43 are housed in the peripheral portion of the rotor 33, being spaced within the rim 33, and their inner ends are suitably fixed to a ferrous metal or magnetic material keeper ring 44 on the inner side of the end plate 35. The opposite or outer ends of the magnets 43 are sealed in openings in the raised peripheral rim of the end plate 36. This exposes the flat ends of the magnets where they are parallel with and in close proximity to Y the inner surface of the diaphragm M. In situations where the pump or other device is intended to handle acids, liquid food products, etc., these active poles or ends of the magnets 43 are protected with caps, sheaths or plating or by a single disc, the same being formed of glass, plastic or other material resistant to the fluid to be handled. There is an equal number of magnets 42 and 43. The external and interna1 magnets 42 and 43 are equally or uniformly spaced circumferentially and are equidistant from the common axis of the shaft 40 and rotor 33.

In accordance with the invention the polarity of the magnets is alternated; i. e., one magnet 42 has its north pole at the diaphragm I4, the next magnet 42 has its south pole facing the diaphragm, the third magnet 42 has its north pole opposing the diaphragm, and so on; and,

in a like manner, one magnet 43 has its south pole at the diaphragm l4, the next magnet has its north pole facing the diaphragm H, the third magnet 43 has its south pole facing the diaphragm, and so on. With this alternated relation of the magnets, the north pole of every other magnet 43 directly opposes the south pole of every other magnet 43, and thesouth poles of the alternate magnets 42 directly oppose the north poles of alternate magnets 43, assuming the motor M or pump to be idle. This relationship is shown in the drawings where the characters N and S represent the north and south poles, respectively, of the two sets of magnets. It will be seen that with this arrangement there are strong magnetic fields or flux flow paths between the opposite poles of the magnets 42 and 43, the thin non-magnetic diaphragm l4 offering a minimum of resistance to the magnetic flow. The carrier 4| serves as a keeper to close the magnetic circuits between the outer ends of the adjacent alternated magnets 42, and the ring 44 serves a like function for the magnets 43 so that there is multiplicity of strong closed magnetic circuits between the opposing ends of the alternated magnets 42 and 43. The magnetic circuits or fields effectively resist relative angular motion between the motor shaft 43 and the rotor 33 thus transmitting rotation from the motor shaft to the rotor, as will be readily understood.

When the pumping loads are heavy, there is slight relative angular movement between the two series of magnets 42 and 43, the magnets 43 tending to lag behind the magnets 42. The extent of this relative movement is approximately one-half of the distance between adjacent magnets 42 so that the related or paired magnets 42 and 43 are axially oflset. It has been found that with the magnets 42 and 43 in this slightly 'oflset relation the drive is capable of transmitting the maximum torque and, because the like poles of the two sets of magnets are closer together at this time, the axial thrust exerted on the rotor 33 by the magnetic drive is reduced to a minimum. This latter feature lessens the frictional resistance to rotation of the rotor 33. It is, of course, important to limit relative angular movement between the motor shaft 40 and the rotor 33 to prevent the like poles of the magnets 42 and 43 from coming into alignment, and for this reason it is desirable to employ a motor M or other driver having a low starting speed and to avoid sudden surges or loads on the pump.

It is believed that operation of the fluidhandling mechanism will be readily understood from the foregoing detailed description. With the motor M in operation, the fields at the sets of magnets 42 and 43 transmit rotation from the motor shaft 40 to the rotor 33. The magnetic drive is through the imperforate diaphragm I4 and it is unnecessary to pass a shaft into the pump chamber to drive the impeller. The diaphragm l4 being positively supported at its periphery by the ring 22 and at its major inner area by the disc 24, may be quite thin to assure a magnetic transmission of high rating and yet resist high bursting pressures. Thus the invention provides a high-pressure magnetically driven pump, or the like. The smooth surfaced hollow rotor 33 has a minimum of fluid drag or resistance while rotating in the pumped fluid and where the fluid handled is a liquid, the sealed rotor practically=fioats so that there is little or no mechanical friction at the bushing 3|. These two features reduce the torque imposed on the magnetic drive and increase the over all efficiency of the pump.

Having described only a typical preferred form of the invention, I do not wish to be limited to the specific details herein set forth but reserve to myself features or modifications that may fall within the scope of the following claims.

I claim:

1. In a device of the character described, a case having a fluid chamber, a shaft secured to the case and extending through the chamber, a rotor means carried by the shaft to act on the fluid within the chamber, a diaphragm secured at its periphery to the case and closing an end of the chamber, means secured to said shaft and supporting the diaphragm against bursting loads, a rotating driver at the exterior of the diaphragm, and magnetic means on the driver and rotor means for transmitting rotation from the driver to the rotor means through the diaphragm phragm and connected with the shaft to sup-.

port the diaphragm against bursting loads exerted by the fluid, a driver at the exterior of the diaphragm, and magnetic means associated with the rotor element and driver for transmitting rotation from the driver to the rotor element.

3. In a device of the character described, a case having a fluid chamber, a diaphragm secured at its periphery to the case and extending across an end of the chamber, a shaft secured to the case and extending through the chamber, a rotor element carried by the shaft within the chamber to act on the fluid therein, a reinforcing part associated with the diaphragm and connected with the shaft to support the diaphragm against bursting loads exerted by the fluid, said part being coextensive with the major inner portion of the diaphragm to reinforce the same and being spaced from the periphery of the diaphragm to leave a limited annular area of the diaphragm free, a driver at the exterior of the diaphragm, and magnetic means associated with the driver and rotor element for transmitting rotation from the driver to the rotor element through said free area of the diaphragm.

4. In a device of the character described, a case having a fluid chamber, a diaphragm secured at its periphery to the case and extending across an end of the chamber, a shaft secured to the case and extending through the chamber, a rotor element carried by the shaft within the chamber to act on the fluid therein, a reinforcing part associated with the diaphragm and connected with the shaft to support the diaphragm against bursting loads exerted by the fluid, said part being coextensive with the major inner portion of the diaphragm to reinforce the same and being spaced from the periphery of the diaphragm to leave a limited annular area of the diaphragm free, a driver at the exterior of the diaphragm, and magnetic means associated with the driver and rotor element for transmitting rotation from the driver to the rotor element through said free area of the diaphragm, the magnetic means including magnets on the driver and rotor element adjacent the external anddnternal surfaces respectively of said free area of the diaphragm.

5. A device of the character described comprising a case having a fluid chamber, a diaphragm extending across an end of the chamber, means securing the peripheral portion of the diaphragm to the case, a stationary shaft attached to the case and extending through the chamber toward the diaphragm, a. reinforcing part coextensive with the major central area of the diaphragm and attached to said shaft to support the diaphragm against bursting pressures exerted by the fluid in said chamber, a rotor element carried by the shaft within the chamber, means on the rotor element for acting on the fluid within the chamber, said part being spaced from said securing means to leave a limited area of the diaphragm free, a driver at the exterior of the diaphragm, and a magnetic drive for transmitting rotation from the driver 8 a to the rotor element including opposing members at the inner and outer surfaces of said free area of the diaphragm.

6. A device of the character described comprising a case having a fluid chamber, a diaphragm extending across an end of the chamber, means securing the peripheral portion of the diaphragm to the case, a stationary shaft attached to the case and extending through the chamber toward the diaphragm, a reinforcing part coextensive with the major central area of the diaphragm and attached to said shaft to support the diaphragm against bursting pressures exerted by the fluid in said chamber, a hollow sealed rotor element carried by the shaft within the chamber, means on the rotor element for acting on the fluid within the chamber, said part being spaced from said securing means to leave a limited area of the diaphragm free, a driver at the exterior of the diaphragm, and a magnetic drive for transmitting rotation from the driver to the rotor element including opposing members at the inner and outer surfaces of said free area of the diaphragm.

'7. A device of the character described comprising a case having a fluid chamber, a diaphragm extending across an end of the chamber, means securing the peripheral portion of the diaphragm to the case, a stationary shaft attached to the case and extending through the chamber toward the diaphragm, a reinforcing disc on the outer side of the diaphragm and secured to the shaft to support the diaphragm against bursting pressures exerted by the fluid in the chamber, the periphery of the disc being spaced from said securing means to leave a limited annular zone of the diaphragm exposed, a rotor supported on the shaft within the chamber, a driver at the exterior of the diaphragm, and a magnetic drive for transmitting rotation from the driver to the rotor including annular rows of magnetic members on the rotor and driver opposing one another at the opposite sides of said zone.

8. A device of the character described comprising a case having a fluid chamber, a diaphragm at an end of the chamber secured at its periphery to the case, a reinforcing part on the diaphragm supporting the same against the bursting pressures exerted by'the fluid in the chamber, a shaft having one end screwed into the case and its other end screwed into said part and extending through the chamber, bushing means on the shaft having thrust transmitting engagement therewith, a rotor in the chamber carried by the bushing means, the shaft being manually rotatable to axially adjust the rotor, a driver at the exterior of the diaphragm, and a magnetic drive for transmitting rotation from the driver to the rotor including magnets on the driver and rotor opposing one another at opposite sides of the diaphragm.

9. In a device of the character described, a case having a fluid chamber, a diaphragm secured at its periphery to the case and extending across an end of the chamber, a shaft secured to the case and extending through the chamber, a rotor element carried by the shaft within the chamber to act on the fluid therein, a reinforcing part associated with the diaphragm and connected with the shaft to support the diaphragm against bursting loads exerted by the fluid, said part being coextensive with the major central portion of the diaphragm to reinforce the same and being spaced from the periphery of the diaphragm to leave a limited annular area of the diaphragm free, a driver at the exterior of the diaphragm, and magnetic means associated with the driver and rotor element for transmitting rotation from the driver to the rotor element through said free area of the diaphragm, said magnetic means including an annular series of spaced magnets on the driver in close relation to the outer surface of said free area, and an annular series of spaced magnets on the rotor element in close relation to inner surface of said free area.

10. In a device of the character described, a case having a fluid chamber, a diaphragm secured at its periphery to -the case and extending across an end of the chamber, a shaft secured to the case and extending through the chamber, a rotor element carried by the shaft within the chamber to act on the fluid therein, a reinforcing part associated with the diaphragm and connected with the shaft to support the diaphragm against bursting loads exerted by the fluid, said part being coextensive with the major central portion of the diaphragm to reinforce the same and being spaced from the periphery of the diaphragm to leave a limited annular area of the diaphragm free, a driver at the exterior of the diaphragm, and magnetic means associated with the driver and rotor element for transmitting rotation from the driver to the rotor element through said free area of the diaphragm, said magnetic means including an annular series of axially arranged bar magnets on the driver having poles in close relation to the outer surface of said free area, and an annular series of axially arranged bar magnets on the rotor element having poles in close relation to the inner surface of said free area to oppose the poles of the first-named magnets.

11. In a device of the character described, a case having a fluid chamber, a diaphragm secured at its periphery to the case and extending across an end of the chamber, a shaft secured to the case and extending through the chamber, a rotor element carried by the shaft within the chamber to act on the fluid therein, a reinforcing part associated with the diaphragm and connected with the shaft to support the diaphragm against bursting loads'exerted by the fluid, said part being coextensive with the major inner portion of the diaphragm to reinforce the same and being spaced from the periphery of the diaphragm to leave a limited annular area of the diaphragm free, a driver at the exterior of the diaphragm, and magnetic means associated with the driver and rotor element for transmitting rotation from the driver to the rotor element through said free area of the diaphragm, said magnetic means including an annular series of axially arranged bar magnets on the driver having poles in close relation to the outer surface of said free area, and an annular series of axially arranged bar magnets on the rotor element having poles in close relation to the inner surface of said free area to oppose the poles of the firstnamed magnets, the polarity of the magnets of each of said series being alternated.

12. A device of the character described comprising a case having a fluid chamber, a dia-- phragm at an end of the chamber, an element turnably supported in the chamber, a driver at the exterior of the diaphragm, and a drive for transmitting angular movement from the driver to said element including an annular series of circumferentially spaced magnets arranged axially of the driver having magnetic pole ends in close facing relation to the outer surface 10 of the diaphragm. a magnetic-material carrier member on the driver magnetically connecting the other ends of said magnets, an annular series of circumferentially spaced axially arranged magnets on said element having magnetic pole ends in close facing relation to the inner surface of the diaphragm, and a magnetic-material member on said element magnetically connecting the other ends of the last-mentioned magnets.

13. A device of the character described comprising a case having a fluid chamber, a diaphragm at an end of the chamber, an element turnably supported in the chamber, a driver at the exterior of the diaphragm, and a drive for transmitting angular movement from the driver to said element including an annular series of circumferentially spaced axially arranged magnets on the driver each having one end magnetic pole in close facing relation to the outer surface of the diaphragm, means magnetically connecting the other end poles of said magnets, an annular series of circumferentially spaced axially arranged magnets on the element each having one end magnetic pole in close facing relation to the inner surface of the diaphragm, and means magnetically connecting the other end poles of the last-mentioned magnets, the polarity of the magnets of each series being alternated in the circumferential direction.

14. A device of the character described comprising a case having a fluid chamber, a diaphragm at an end of the chamber, a hollow sealed element supported in the chamber for angular movement, a driver at the exterior of the diaphragm, and a drive for transmitting rotation from the driver to said element including an annular series of circumferentially spaced magnets on the driver having magnetic poles in close facing relation to the outer surface of the diaphragm, and an annular series of circumferentially spaced magnets on said element having magnetic poles in close facing relation to the inner surface of the diaphragm.

15. In a fluid handling device the combination of, a case having a fluid chamber, a diaphragm secured at its periphery to the case and extendins across an end of the chamber, a shaft carried by the case and extending through the chamber, an element in the chamber supported by the shaft for angular movement, a reinforcing part connected with the shaft and supporting the diaphragm against bursting loads exerted by the fluid in the chamber, a driver at the exterior of the diaphragm, and magnetic means associated with the driver and said element for transmitting angular movement from the driver to said element.

JESSE D. STAGGB.

REFERENCES CITED The following references are of record in the die of this patent:

UNITED STATES PATENTS Number Name Date 2,003,163 Warren May 28, 1935 2,429,114 Whitted Oct. 14, 194'! 2,444,687 Widakowich July 8, 1948 I FOREIGN m'rnn'rs Number Country Date 192,618 Great Britain Feb. 8, 1923 

